The answer
First: during this time, He taught them about the kingdom of God, whether by His appearances or His teachings (Acts 1:3).
Second: had He ascended to the heavens within a few hours or days of His resurrection, they might have thought that they had just been hallucinating.
Third: during this period, He appeared to others, as the apostle Paul says: “After that, He appeared to more than five hundred of the brothers and sisters at the same time” (1 Cor. 15:6).
Fr. Tadros Yacoub Malaty